The general objective is to identify and isolate antigenic variants of CEA and related glycoproteins of the human digestive system, and to investigate their physicochemical, immunological, and diagnostic properties. CEA and CCA-II is purified from liver metastases of colon adenocarcinoma by perchoric acid extraction and fractionation by molecular sieve, ion-exchange, and lectin and antibody affinity chromatography. CCA-III is purified from tumors and normal spleen by similar procedures. Goat and rabbit antisera raised against these antigens are used for the development by affinity chromatography of antibodies possessing different CEA, CCA-II, and CCA-III immunological specificities. Antigen species bearing these determinants in plasma and tissue specimens from normal individuals and patients with malignant and non-malignant gastrointestinal disease will be studied by radioassay, immunohistochemical, and physicochemical procedures.